Direct Halogenation of Alcohols and Their Derivatives with tert‐Butyl Halides in the Ionic Liquid [pmIm]Br under Sonication Conditions – A Novel, Efficient and Green Methodology

A novel halogenating reagent system for direct halogenation of alcohols has been developed. tert‐Butyl bromide, chloride and iodide in combination with the ionic liquid [pmIm]Br have been found to convert alcohols into the corresponding bromides, chlorides and iodides under sonication conditions (or heating) in good yields. Although a variety of primary and secondary alcohols participated in this reaction without any difficulty, tertiary alcohols remained inert. Several alcohol derivatives such as OTMS, OTBDMS, OAc, OTS and OTHP are also transformed into the corresponding halides in one‐pot fashion by this procedure. A plausible rationale for this transformation is also presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)